Slip-regulator control



May s. 1928.

G. H. JUMP SLIP REGULATOR CONTROL Filed June 21. 1926 inventor 1 George H. Jump, y His Akbar-neg,

atcnted May 8, 1928. 'I

. UNITED STATES PA TENT @FFHCE.

I GEOBGE H. JUMP, OI BUFFALO, NEW YORK, ASBIGNQB 1'9 GENERAL mo COMPANY, A COBZEORATION OF NEW YGBK.

BLIP-REGULATOR CONERGL.

Application filed June 21, 1828. serial Io. 112338.

' My invention relates to the control of liquid'slip regulators, which are commonly provided for automatically regulating the slip of an alternating current motor so as to permit a fly-wheel or other inertia device connected with the motor to assist 1n carryina peak loads thrown on the motor.

iniquid sli regulators are commonly rovided with e ectrodes, the position of w ich 9 may be varied in order to vary the resistance of the regulator and thus control the slip of the motor controlled. The Wei ht of hose electrodes is ordinarily counterba ance'd in such a way that the electrodes have a 5 small tendency or bias to assumethe minimum resistance position. An electroresponsive device, such as a torque motor, is automatically provided for varying the position of the regulator electrodes and this device 9 is customarily energized in accordance with the load on the motor, the slip of which is to be controlled. The torque motor or other electroresponsive'device operates to raise the electrodes and thus automatically control the resistance of the regulator in accordance With the load on the main motor. With such an arrangement, when the main motor is connected to its source of supply, the torque motor will be energized by the rush of current taken by the main motor so as to operate the electrodes to the maximum resistance position, but by reason of the fact that the electrodes are initially in the minimumresistance position, the current taken by the motorwhen it'is initially connected to its source of supply will be excessive and the strains on the various parts will be abnormal.

@ne of the objects of my invention is to insure that the main motor will not be initially connected to its source of supply unless the regulator electrodes are in their high resistance position so that when the motor is connected to its source of supply the current taken by the motor will be within reasonable limits, and the acceleration of the motor. will be smoothly accomplished.

Alternating current induction motors are sometimes stopped either by reversing the connections of the motor to a source of supply, or by disconnecting the motonfrom the alternating current supply and connecting the field windings thereoi to a direct current source of supply. In each case, the motor acts as a braking generator to quickly retard the load. When the motor is-thus used. as a braking generator, it is desirable that the regulator electrodes be in a hi h resistance position in order that the bra ing torque of the motor may. be limited to reasonable values.

A further object of the invention is to insure that the regulator electrodes will be in a high resistance osition before the braking connections of t e motor are established. A still further object of the invention is to 'efi'ect the control of the slip regulator by automatic means which function Without any attention on the part of the operator to insure that the regulator electrodes will be in a desired position for taking care of the conditions encountered.

In carrying my invention into eflect in the form which I now regard as the preferred form thereof, an auxiliary counterweight is provided for the electrodes of the regulator and this auxiliary counterweight is automatically operated by an auxiliary motor which is controlled automatically in response to the operation of switch mechanism provided for connecting the motor to an alternating current source of sup iy and for establishing the braking connections for the motor. The auxiliary motor is interconnected with said switch mechanism in such a" manner that the switch mechanism cannot be closed unless the regulator electrodes are in a high resistance osition. In

this manner, the functioning oft e slip regulator is entirely automatic and no special precautions need be taken by the operator s1nce an incorrect operation is prevented by the improved system.

For a better understanding of the invention, reference is had to the accompanying drawing in which I have shown in very diagrammatic form; an embodimentof the invention for the purpose of explaining the principles thereof. The main electric motor 10 is indicated as of the three-phase wound rotor type, and is provided for the purpose of driving a load not shown).

The flywheel 11 is connected with the motor. 10 so as to assist the motor in taking careof peak load conditions. The liquid slip regulator 12 is connected in the rotor circuit of the motor for the customary purpose of increasing the resistance in the slip rin sir cult of the motor when the current input to the stator of the motor exceeds a prede- Ill termined amount so as to thereby limit the torque output of theinduction motor an permit the flywheel to give up some of its stored energy. The kinetic energy of the i 6 flywheel is given up by an increase in the slip of the induction motor to an extent dependent on the mechanical power demand at the motor shaftin excess of the torque delivered by the motor itself.

The regulator is provided with stationary electrodes 13 and cooperating movable electrodes It. The weight of the movable electrodes, the supporting member 15 therefor and the weight of the other moving parts of re the regulator are partially counterbalanced by a eounterbalancing weight 16 which is eonnected with the ri ht hand arm or the lever 17, the left han arm 18 ct which is connected to the movable electrodes of the an regulator. The counterbalance 16 is of such a value that the electrodes 14 have a slight bias or tendency to move to the minimum resistance position. The movable electrodes are varied in position in response to the w load on the motor 10 by means-of a torque motor 19 of the three-phase alternating cur rent type energized from the secondaries oi the current transformers 20 having their primaries included in the stator circuit of the' to motor 10.

The motor 10 is connected to its source of supply 21 (after the disconnecting switch 22 is closed) by means of the electromagnetic switch or contactor 23. The contactor 24 3 is provided for connecting the motor with the direct current supply circuit 25 so as to establish braking relations for the motor. The contactors 23 and 24 are suitably electrically interconnected in the customary manto ner to prevent simultaneous closure thereof.

The contactors 23 and 24 areenergized under the control of a master switch 26 operating through the electromagnetic relays 27 and 28, the relay 27 being provided for enas ergizing the line contactor 23 and the relay 28 being provided for energizing the brake contactor 24.

In order to insure that the regulator electrodes 14 will be in their maximum resist- B9 ance position when themotor is either initially connected to the source of supply 21 or connected to the source of supply 25 for braking, l have provided the auxiliary counterweight 29 which cooperates with the 85 counterweight 16 to bias the electrodes 14 tothe position shown in the drawing. The limit switches 30 and 31 cooperate with the counterbalances 29 and 16 so as to insure that the regulator electrodes will be in the to desired position at the proper time. The auxiliary counterweight 29 is raised and lowered with respect to counterweight 16 by means of the auxiliary motor 32 which is controlled by limit switches 30 and 31 and u by auxiliary switch mechanism connected with the contactors 23and24 for the objects (1 stated.

As thus constructed and l arranged and with the partsdn their respective positions indicated in the drawing the operation ofmy invention is as follows: 7

The disconnecting switch 22 will first be closed and the master switch 26 will be moved to make engagement with its right hand terminal, thereby energizing the run relay 27 through a circuit from the direct current supply circuit 33. The line contactor 23 will thereb be energized through a circuit from the lower conductor of the-source of supply 33, upper contacts associated with limit switch 39, contacts of relay 27, winding of line contactor 23, upper auxiliary switch 34-. associated with brake contactor 24 to the upper conductor of a supply Cll,

"cuit 33. By reason of the fact that the movable electrodes are in their. upper or high resistance position, this energization of the line contactor 23 is permitted. When the line contactor closes it is mechanically held in theclosed position, independently of control by the master switch 26, by means of the electromagnetic detent 35;.

Upon the closing of the line contactor 23, the auxiliary motor 32 of the regulator is energized through a circuit from the upper conductor of the supply circuit 33, limit switch 31, manual switch contact 36, auxiliary switch contacts 37 associated with line contactor 23 to the lower conductor of the between motor 32 and the counterbalance 29, the counterbalance will be maintained in this elevated position independently of the interruption of the supply of current to the motor 32. When the electrodes 14 are lowered a predetermined amount under the control, of the torque motor 19, the limit switch 30 will be released to move in accordance with its bias and make engagement with its lower set of contacts. However, with the motor 10 connected to the source of supply 21, this will produce no eile ct at this time. i I

In order to disconnect the motor'10 from the supply circuit 21, the push button 38 is closed and the release electromagnet 39 is energized to release the catch 35. When the line contactor 23 opens (it has been assumed that the master switch 26 has been returned to the neutral position shown) the auxiliary motor 32 of the regulator willbe automatically energized to lower the aux iliary counterbalance 29 and thus cause the their positions shown in. the drawing and by Letters Potent or the regulator electrodes to be raised to their itions-shown in the drawin'. The auxlliarymotor 32 will be energized through the lower contacts of limit switch 30, manual switch contacts 40, lower auxiliary switch contacts 41 associated with brakccontactor 24 and lower contacts of the auxiliary switch associated with line contuctor 23 to the lower conductor of supply circuit 33. Until the electrodes have been raised to the limit switch 3% has been operated to interrupt the circuit through the lower set of contacts and close the circuit through its upper set of contacts neither contactor 23 nor contactor 24: can be energized to close. This is to insure that the motor ill can neither be connected to its supply circuit 21 for normal running nor to supply circuit 25 for braking unless the regulator electrodes are in a high resistance position.

Under certain circumstances, it may be desirable for the operator to place the mastcr switch 26 in contact with its left hand 7 contact after the energization and closing of the line contact or 23 so that when the push button 38 is operuted to disconnect the motor 10 from the supply 21, the braking connections for the motor will. be outomati-' cally established es soon as the regulator contacts are in their high resistance position. The brake contactor 24 is also provided with an electromagnetically controlled retaining catch 43 so as to hold the brake contactor closed independently of the master switch 26, After the brake contactor 2% is closed, the auxiliary motor 32 will be energized to raise the auxiliary counterbalance 29 and thus permit the electrodes 14: to gradually assume their minimum resistance position. If at any time during the operation of the equipment with the motor connected to the supply circuit 21, it is desired that the electrodesidbe varied from the position in which these electrodes are held by the torque motor 19, the operator may eiiect such control through manually operated switch 44. The interconnections of this push button switch 44- with the line contactor 23 and the brahe contactor 24: are such that the auxiliery motor 32 may be at any time energized to lower the counterbalance 29 and thus raise the electrodes M by operating the switch it into engegement with its right hand side of contscts.

I claim as new and desire to secure United States, is,

i. combinetion, e driving motor, a liquid slip regulator therefor having movable electro *es for verying the elfective resistance of the regulator, menus operated responsively to the load on said motor for automatically varying the position of said electrodes, switch mechanism for connecting said motor to a source of supply, and means autometi= cally controlled by said switch mechanism for governing said electrodes independently "of said first mentioned means to insure that said electrodes Will be in a high resistance of supply, and means governed by said c switch mechanism for supplementing said counterweight to necessitate that said electrodes be in a high resistance position before the said switch mechanism is operative t connect the motor to the source of sup lv;

3. In combination, a liquid slip regulator having movable electrodes for varying the effective resistance of the regulator, the said electrodes being normally biased to a low resistance position, a torque motor for sutomatically varying the position of said electrodes in accordance with predetermined conditions, a counterweight for said elec trodes, and means for automatically govern ing the said counterweight to insure that said electrodes will be in a high resistance position under predetermined conditions independently of said torque motor.

4-. In combination, a driving motor, a, if

uid slip regulator therefor having movable ii electrodes for varying the efiective resistance of the regulator, a counterweight said electrodes whereby the electrodes have a slight bias to move to a low resistance position, means responsive to the load on said motor for automatically varying the position of said electrodes, switch mechanism for controlling the energization of said motor,

an auxiliary counterweight for said electrodes, an auxiliary motor for controlling said auxiliary counterweight, and electrical interconnections between said switch mechanism and said auxiliary motor necessitating the said electrodes being held in ahigh resistance position by said auxiliary coun rweight before said switch mechanism ma be closed and providing means whereby the said auxiliary motor is energized to remove the biasing eii'ect of said auxiliary counterweight on said electrodes when said switch mechanism is closed.

5. In combination, a driving motor, a uid slip regulator therefor having movable electrodes for varying the resistance of regulator, it counterweight for said electrodes of such value that the electrodes have a bias to the minimum resistance position, means operated responsively to the load on the motor for automatically varying the position of said electrodes, switch mechanism lit;

ply, an auxl iary counterweight for said trodes, 'switch mechanism for connecting electrodes, and means governed by said said driving motor to.- a source of supply, 7 switch mechanism for controlling said auxmeans governed by said switch mechanism a ilia'ry counterweight to insure that said elecfor insuring that said electrodes will be in trodes will be in a high resistance position a high resistance position before said driving 20 before said motor is connected to the source motor is connected to the source of supply, of supply. 7 a and manual controlling means for said elec- 6. In combination, a driving motor, a 1i trodes for var in the position thereof in- 10 aid slip re ulator therefor .having movab? dependently 0 said torque motor.

electrodes or varying the resistance of the In witness whereof, I havehereunto set 86 regulator, a counterweight for said elecmy handthis 18th day of June, 1926. trodes, a torque motor operated responsive- 1y to the load on said driving motor for au- 7 GEORGE H. JUMP.

for connectin said motor'to a source of suptomatically varying the position of said elecl 

